Keep Scene resolutions in sync
This script will apply the resolution of the first scene to all other scenes. It will auto-update all scenes as soon as you change the resolution in the first scene.

import bpy

def set_resolution(scene):
    x = bpy.data.scenes[0].render.resolution_x
    y = bpy.data.scenes[0].render.resolution_y
    for scene in bpy.data.scenes:
        scene.render.resolution_x = x
        scene.render.resolution_y = y

bpy.app.handlers.depsgraph_update_pre.append(set_resolution)


All you have to do is run the script once after opening your project in the Scripting workspace.